File indexing completed on 2024-05-12 04:19:52

 /*
 Gwenview: an image viewer
 Copyright 2019 Steffen Hartleib <steffenhartleib@t-online.de>
 
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.
 
 */
 // Self
 #include "twofingerpan.h"
 
 // Qt
 #include <QGraphicsWidget>
 #include <QTouchEvent>
 #include <QVector2D>
 
 // KF
 
 // Local
 #include "gwenview_lib_debug.h"
 #include "lib/touch/touch_helper.h"
 
 namespace Gwenview
 {
 struct TwoFingerPanRecognizerPrivate {
     TwoFingerPanRecognizer *q = nullptr;
     bool mTargetIsGrapicsWidget = false;
     qint64 mTouchBeginnTimestamp;
     bool mGestureTriggered;
     qint64 mLastTouchTimestamp;
 };
 
 TwoFingerPanRecognizer::TwoFingerPanRecognizer()
     : QGestureRecognizer()
     , d(new TwoFingerPanRecognizerPrivate)
 {
     d->q = this;
 }
 
 TwoFingerPanRecognizer::~TwoFingerPanRecognizer()
 {
     delete d;
 }
 
 QGesture *TwoFingerPanRecognizer::create(QObject *)
 {
     return static_cast<QGesture *>(new TwoFingerPan());
 }
 
 QGestureRecognizer::Result TwoFingerPanRecognizer::recognize(QGesture *state, QObject *watched, QEvent *event)
 {
     // Because of a bug in Qt in a gesture event in a graphicsview, all gestures are trigger twice
     // https://bugreports.qt.io/browse/QTBUG-13103
     if (qobject_cast<QGraphicsWidget *>(watched))
         d->mTargetIsGrapicsWidget = true;
     if (d->mTargetIsGrapicsWidget && watched->isWidgetType())
         return Ignore;
 
     switch (event->type()) {
     case QEvent::TouchBegin: {
         auto touchEvent = static_cast<QTouchEvent *>(event);
         d->mTouchBeginnTimestamp = touchEvent->timestamp();
         d->mLastTouchTimestamp = touchEvent->timestamp();
         d->mGestureTriggered = false;
         state->setProperty("delayActive", true);
         state->setHotSpot(touchEvent->touchPoints().first().screenPos());
         return TriggerGesture;
     }
 
     case QEvent::TouchUpdate: {
         auto touchEvent = static_cast<QTouchEvent *>(event);
         const qint64 now = touchEvent->timestamp();
         const QPointF pos = touchEvent->touchPoints().first().pos();
         state->setHotSpot(touchEvent->touchPoints().first().screenPos());
 
         if (touchEvent->touchPoints().size() >> 2) {
             if (d->mGestureTriggered) {
                 d->mGestureTriggered = false;
             }
             return CancelGesture;
         }
 
         if (touchEvent->touchPoints().size() == 2) {
             if (touchEvent->touchPointStates() & Qt::TouchPointReleased) {
                 if (d->mGestureTriggered) {
                     d->mGestureTriggered = false;
                     return FinishGesture;
                 }
             }
 
             if (now - d->mTouchBeginnTimestamp >= Touch_Helper::Touch::gestureDelay) {
                 state->setProperty("delayActive", false);
 
                 // Check if both touch points moving in the same direction
                 const QVector2D vectorTouchPoint1 = QVector2D(touchEvent->touchPoints().at(0).startPos() - touchEvent->touchPoints().at(0).pos());
                 const QVector2D vectorTouchPoint2 = QVector2D(touchEvent->touchPoints().at(1).startPos() - touchEvent->touchPoints().at(1).pos());
                 QVector2D dotProduct = vectorTouchPoint1 * vectorTouchPoint2;
 
                 // The dot product is greater than zero if both touch points moving in the same direction
                 // special case if the touch point moving exact or almost exact in x or y axis
                 // one value of the dot product is zero or a little bit less than zero and
                 // the other value is bigger than zero
                 if (dotProduct.x() >= -500 && dotProduct.x() <= 0 && dotProduct.y() > 0)
                     dotProduct.setX(1);
                 if (dotProduct.y() >= -500 && dotProduct.y() <= 0 && dotProduct.x() > 0)
                     dotProduct.setY(1);
 
                 if (dotProduct.x() > 0 && dotProduct.y() > 0) {
                     const QPointF diff = (touchEvent->touchPoints().first().lastPos() - pos);
                     state->setProperty("delta", diff);
                     d->mGestureTriggered = true;
                     return TriggerGesture;
                 } else {
                     // special case if the user makes a very slow pan gesture, the vectors a very short. Sometimes the
                     // dot product is then zero, so we only want to cancel the gesture if the user makes a bigger wrong gesture
                     if (vectorTouchPoint1.toPoint().manhattanLength() > 50 || vectorTouchPoint2.toPoint().manhattanLength() > 50) {
                         d->mGestureTriggered = false;
                         return CancelGesture;
                     } else {
                         const QPointF diff = (touchEvent->touchPoints().first().lastPos() - pos);
                         state->setProperty("delta", diff);
                         d->mGestureTriggered = true;
                         return TriggerGesture;
                     }
                 }
             } else {
                 state->setProperty("delta", QPointF(0, 0));
                 state->setProperty("delayActive", true);
                 d->mGestureTriggered = false;
                 return TriggerGesture;
             }
         }
         break;
     }
 
     case QEvent::TouchEnd: {
         auto touchEvent = static_cast<QTouchEvent *>(event);
         if (d->mGestureTriggered) {
             d->mGestureTriggered = false;
             state->setHotSpot(touchEvent->touchPoints().first().screenPos());
             return FinishGesture;
         }
         break;
     }
 
     default:
         return Ignore;
     }
     return Ignore;
 }
 
 TwoFingerPan::TwoFingerPan(QObject *parent)
     : QGesture(parent)
 {
 }
 
 } // namespace